birth (n.)
early 13c., from a Scandinavian source such as Old Norse *byrðr (replacing cognate Old English gebyrd "birth, descent, race; offspring; nature; fate"), from Proto-Germanic *gaburthis (cognates: Old Frisian berd, Old Saxon giburd, Dutch geboorte, Old High German giburt, German geburt, Gothic gabaurþs), from PIE *bhrto past participle of root *bher- (1) "to carry; to bear children" (cognates: Sanskrit bhrtih "a bringing, maintenance," Latin fors, genitive fortis "chance;" see bear (v.)).

Suffix -th is for "process" (as in bath, death). Meaning "parentage, lineage, extraction" (revived from Old English) is from mid-13c. Birth control is from 1914; birth rate from 1859. Birth certificate is from 1842.
birth (v.)
mid-13c., from birth (n.). Related: Birthed; birthing.